Muriel Lederman

Characterization of a mutagenic bacterial product in human feces

Mutagens detectable with the Ames assay have been found in the feces of apparently healthy individuals and the incidence of this mutagenic activity was found to be greater in a population at high risk for colon cancer than in a population at low risk. A compound accounting for the mutagenic activity has been isolated by high performance liquid chromatography. Two closely related forms which behave identically chemically could be resolved. The compound was active on Salmonella typhimurium TA98 and TA100, had a characteristic ultraviolet absorption spectrum with maxima at about 320, 340, and 365 nm, fluoresced green in long wavelength ultraviolet light, and had the same mobility on the thin-layer chromatography as the mutagenic activity in a direct ether extract of feces. The compound was unstable in air but could be stabilized in the presence of butylated hydroxytoluene. Upon oxidation the compound lost its mutagenicity and its ultraviolet absorption spectrum underwent a blue shift so that the absorption maxima were at 295, 310, and 325 nm. Determination of the structure of the mutagen has been difficult since the compound was not volatile and production of a volatile derivative has not been successful. On thin-layer chromatography plates the compound reacted with reagents that detect chlorinated compounds. By thermal energy analysis it did not appear to contain a nitroso group. The compound increased in concentration upon anaerobic incubation of feces at 37 C and this increase was prevented by cold, air, and antimicrobial agents. This suggests to us that the fecal flora produces the compound.

In vitro production of human fecal mutagen

The feces of some normal humans were previously shown to be mutagenic by the Salmonella mutagenicity assay with strain TA100. In the present study, the mutagenicity of feces of certain donors can be increased by anaerobic incubation for 96 h. The increase in mutagenicity did not occur upon incubation in the cold or in air, in the presence of antimicrobial agents or if the feces were sterilized by heat. On thin-layer chromatographs, the relative mobility of fecal mutagen for all donors after incubation was the same in any one of 4 different solvent systems. The major mutagenicity appears to be due to a single type of compound which may be produced by anaerobic bacteria.

Research note: Genes on chromosomes: The conversion of Thomas Hunt Morgan

In the first decade of the twentieth century, the foundation for the science of genetics was set. In 1900, the data of Gregor Mendel were rediscovered. By 1915, a community of scientists accepted that there were entities on chromosomes that controlled the development of observable traits. During the intervening period, Thomas Hunt Morgan was one of the major skeptics regarding the chromosomal location of the genes. His acceptance may have been the turning point for the flowering of American genetics. This paper will discuss the reasons for Morgans recalcitrance, his conversion to belief, and the nature of the scientific evidence that led to his acceptance.

Structuring feminist science

Synopsis Many calls for a feminist science have ended with the disclaimer that there is no way to imagine such a science from within an androcentric society. Making the attempt requires dealing with two broad questions: “Is all or some of science socially constructed?” and “By what features is science recognized?” The strategy used here involves defining the components as we know them, asking if they are socially constructed, and, if they are, how they could be changed to be less androcentric. The conclusion is that all of science may be androcentric, and the approach to attaining feminist science may need to be radical, a total replacement of the scientific enterprise with one not based on the scientific method. Alternatively, we may accept a modification of current science, a “feminized” science (defined as doing the same science differently), as consistent with the political goal for feminist scientists.

Possible sequences for nuclear accumulation of parvoviral proteins

Parvoviral genomes have been searched for sequences which may code for the nuclear transport of viral proteins. Sequences similar to those which regulate the nuclear transport of T antigen and yeast mating type protein were detected within the sequences coding for capsid and non-capsid proteins.

Social and Gendered Readings of Illness Narratives

This essay recognizes that the interactions that define medical care are problematic and that narrative is invoked to overcome these strains. Being grounded in science, medicine, too, might be influenced by a particular world-view that arose in the natural philosophy of the Scientific Revolution. If narrative responds to this sort of medicine, it may retain traces of this mindset. A feminist approach responds to this viewpoint and may used beneficially to analyze both the story of medicine and the stories within medicine. Tensions discussed from this perspective are those between sickness and health and those between patient and provider; also questioned are suitable form(s) of narrative and whose narratives are valued. Suggestions for broadening narrative to address these issues include letting the body speak for itself, overcoming the power differential in the patient/provider interaction and using standpoints to foster a more equal and just medical system.